Higher phosphorus intake leads to lower 1,25-dihydroxyvitamin D in humans.

1 mg/dL increase in plasma phosphorus levels= decrease in natural 1,25-dihydroxyvitamin D by -19 pg/dL

Observational study: Serum phosphorus inversely related to testosterone and estradiol in older men
Participants (a): 1,346 community-living older men. Mean age = 76
Particpants (b): Results were confirmed in an independent sample of 2,555 older men
- Causation is unclear.

Observational study: Association of serum inorganic phosphate with sex steroid hormones and vitamin D in a nationally representative sample of men
"We found a lack of statistically significant difference in geometric means of Pi across quintiles of concentrations of sex hormones, indicating a tight regulation of Pi."
"Our findings suggest a weak link among sex hormones, vitamin D, and Pi in men."

Observational study: Phosphorus as predictive factor for erectile dysfunction in middle aged men: A cross sectional study in Korea
Participants: 1,899 police men aged 40 to 59 years
Finding: serum phosphorus was strongly associated with erectile dysfunction.
- Causation is unclear.